Bullet traps per se are well known devices which have been used for many years by firearm manufacturers who are faced with the need to proof, function fire and target firearms such as handguns, rifles and shotguns. In this context, "proof" means test firing a firearm at a higher load of ammunition, usually 40% greater, than the regular load specified for the barrel of that firearm; "function fire" means test firing the firearm through its full cycle of functions; and "target" means test firing the firearm for accuracy. The objectives of such devices have been to provide means located at a relatively short distance from the shooter to catch the lead or other types of bullets (jacketed or unjacketed) and prevent either the ricochet of a whole bullet or a large fragment thereof or the backsplattering of numerous small metal particles, which could return with enough energy to cause injury to the shooter or innocent bystanders, and to collect the waste lead, brass and jacket material. The known types of bullets traps have run the gamut from wood boards to sand-filled boxes to metallic funnel and deceleration chamber combinations.
Merely by way of example, a known sand-type bullet trap consists of a quantity of sand in a hardwood box set against a concrete backstop or wall. However, a bullet trap of this class has a number of drawbacks and disadvantages, both in terms of its structural and functional characteristics and in terms of the expenses associated with it. The material requirements for the box are, for example, 640 linear feet per year of 2".times.8".times.10' hardwood, and 45 cubic yards per year of sand. Annual maintenance requires 8 man-hours per week for 50 weeks. Disposal of such a sand/wood trap and accumulated waste requires handling a load of about 15 tons per year, including transportation to a landfill. Assuming 5-6 loads per year, annual expenditures at current costs (including labor) come to about $30,000 plus the cost of the sand and hardwood, for an aggregate total of about $40,000. Moreover, under current environmental laws, lead has been banned from landfills unless it has first been treated to meet new disposal standards, and the separation of lead from the sand and the detoxification treatment thereof (e.g., a thermal oxidation, which has been proposed for this purpose) can easily double or triple the disposal costs.
On the other hand, the mechanical bullet traps of the funnel and deceleration chamber type, which came onto the market about a century or so ago, were specifically designed to deal with some of the problems that were inherent to the sand-filled box types of traps. Some representative relatively simple bullet trap constructions of the funnel and chamber type are disclosed in U.S. Pat. Nos. 385,546 (Decumbus 1888); 694,581 (Reichlin 1902); 840,610 (Easdale 1907); 2,013,133 (Caswell 1935); and 4,126,311 (Wagoner 1978). Somewhat more sophisticated bullet trap constructions are disclosed in U.S. Pat. Nos. 1973); 4,512,585 (Baravaglio 1985); and 4,821,620 (Cartee et al. 1989).
Of the first-mentioned set of these bullet traps, to the best of my knowledge none are in current commercial use, primarily because they were not designed for and were incapable of withstanding the impacts of high power steel-jacketed ammunition, but also because they tended to deteriorate rather rapidly even under the impacts of relatively low power ammunition. In essence, this was due not only to the fact that the steel or like metal of which the impact plates defining the funnel and the initial contact region of the deceleration chamber were made was generally of a relatively low grade in terms of its composition (carbon content, etc.) and strength, but also to the fact that the impact plates were generally arranged at relatively high angles (30.degree.-60.degree.) to the bullet flight path. Bullets coming into contact with such impact plates at high momentum and at relatively large angles invariably ricochet from one of the funnel impact plates to the other at relatively high angles of incidence and ultimately impact at a high angle against the interior surface of the circumferential boundary wall of the deceleration chamber and bounce along the same from point to point. This has not only resulted in a shattering and fragmentation of the bullets but also in a relatively high rate of deterioration of the impact plates and the deceleration chamber wall and frequent occurrences of penetration thereof by the bullets or fragments thereof. The escape of a bullet or its fragments from confinement in the chamber, of course, further entails the danger of injury and even death to the shooter or an innocent bystander and also, where the bullets are made of lead, contributes to lead pollution of the environment.
Even the more recent ones of the patented bullet traps, however, some of which, to the best of my knowledge, may currently be in use, have been beset by numerous drawbacks, including high original equipment manufacturing, installation and maintenance costs, the need for frequent replacement of baffle or impact plates which are damaged through scoring, erosion and penetration by bullet impacts, the need for minimizing lead build-up and for controlling the problem of lead dust (airborne lead dust must be eliminated using sophisticated vacuum systems), and the need for dealing with hazardous waste (handling, collection/separation, transportation and disposal). Moreover, such bullet traps are generally not multi-functional, i.e., they cannot be used to proof, function fire and target firearms in one system because their impact plates would be demolished by the high load ammunition used in proofing. Also, these traps are usually limited by their design for use with either handguns or high powered rifles but not both.